Role of cement alkali content in acid attack: A pore-solution and pore-size-distribution study

Abstract

The behavior of hydrated portland cement pastes in an acid‐buffered solution of acetic acid/sodium acetate (HAc/NaAc) (pH 4.5) during a period of 90 days at a temperature of 21°C has been studied. The changes that were caused by the acid ingress were monitored via analysis of the extracted pore solution. The evolution of the porosity and pore‐size‐distribution changes were evaluated by using intrusion mercury porosimetry, and those of crystalline compounds were evaluated by using X‐ray diffractometry. A similar study was conducted with an equivalent series of samples that were immersed in distilled water. The results showed the important role that cement alkali content (1.03% K2O, 0.2% Na2O) has in the mechanism of the acid attack. Interesting correlations were established between pore‐solution and porosity data.